Control apparatus



r- 1960 w. B. HAMELINK 2,924,720

CONTROL APPARATUS filed Dec. 2. 1957 2 Sheets-Sheet 1 WILLIAM B. HAMELINK ATTORNEY Feb. 9, 1960 w. B. HIAMELINK 2,924,720

CONTROL APPARATUS Filed Dec. 2, 1957 T0 CIRCUIT TO BE CONTROLLED 2 Sheets-Sheet 2 +Il +ll 8 8 2 3.. "1*

0 Al 39! g, m 9 W P z Q N g I g x m 5 T w INVENTOR.

WILLIA M B. HAMELINK A 7' TORNE Y CONTROL APPARATUS William B. Hamelink, Richfield, Minn., assignor to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn., a corporation of Delaware Application December 2, 1957, Serial No. 699,996

7 Claims. (Cl. 25083.6)

The present invention is concerned with an improved control apparatus and more particularly with a condition responsive control apparatus utilizing a Geiger tube of the non-self quenching type as a condition sensor. The co-pending application of Robert O. Engh, Serial No. 646,125, filed March 14, 1957, discloses a condition detecting apparatus utilizing a Geiger tube of the non-self quenching type in which means provides time delay to prevent operation of the Geiger tube until the Geiger tube quenching circuit is in a condition to perform its quenching operation. 7

Upon' the initial application of operating voltage to ,the non-self quenching type Geiger tube, itis possible for the Geiger tube to pass a sustained currentfor a relatively long period of time before the quenching circuit becomes operative to perform its quenching function. This is particul'arlytrue where the quenching circuit incorporates a hot cathode type discharge device which requires a period of time for the cathode to be heated to electron emissive' temperature. This sustained discharge of the Geiger tube is not particularly detrimental to the Geiger tube in most cases,but the discharge does render the Geiger tube unstable for a given period of time thereafter. This instability 'is undesirable,

. particularly in the case of a condition detecting apparatus which is continuallyenergized andis utilized to supervise a particular-area for a condition such as a fire.

vFor example, a power failure may occur and upon the ing Geiger tube and a quenching circuit therefore wherein integrating means are provide to delay the application of operating voltage to theGeiger tube until the quenching circuit is in a condition to perform its quenching operation.

-It is a further object of the present invention to provide an improved control apparatus utilizing a non-self quenching Geiger tube having quenching means including an electron discharge device of the hot cathode type,

and including integrating means connected to delay the application of operating voltage to the Geiger tube until the hot cathode discharge device is heated to operating temperature. g

It is a further object of the present invention to provide an improved control apparatus using a non-self quenching Geiger tube-and a quenching circuit including a gas filled hot cathode discharge device wherein integrating means are provided to delay the application of operating voltage to the" Geiger tube and to the gas filled discharge device until the cathode of said discharge device is heated to operative temperature.

United States Patent 2,924,720 Patented Feb. 9, 1960 ice 7 present invention.

Referring specifically to Figure 1, the reference numeral 10 designates generally the condition sensor in the form of a Geiger tube having an anode 11 and a cathode 12 disposed in a ionizable gaseous medium. This Geiger tube 10 is connected to a quenching circuit including a gas filled discharge device 13 having an anode 14, a control electrode 15, a cathode 16, a cathode heater 17, and a further electrode 18.

The output of the quenching circuit including discharge device 13 is applied to a further electronic stage including a discharge device 19 having an anode 20,

control electrodes 21 and 22, cathode 23, cathode heater 24, and a further electrode 25. The electronic stage incorporating discharge device 19 is of the type described in the co-pending Fred T. Deziel application, Serial No. 592,767, filed June 21, 1956, now abandoned. The output of the electronic stage including discharge device 19 is connected to a further electronic stage including a discharge device 26 having an anode 27, a cathode 28, a cathode heater 29 and a control electrode 30.

The anode 27 of discharge device 26 is connected to the input of a further electronic stage including a discharge device 31 having an anode 32, a cathode 33, a cathode heater 34, and a control electrode 35. The

output of this discharge device 31 is the output of the control apparatus and includes a relay 36 having a winding 37 which is connected to the anode of discharge device 31. Relay 36 includes a normally opened switch 38 which is adapted to be closed upon the'winding 37 of this relay being energized. The switch 38 may provide a variety of functions and for purposes of simplicity, it has been labeled in Figure 1 as being connected to a circuit to be controlled.

Operating voltage for the control apparatus is derived from, transformers 39 and 40. Transformer 39 is provided with a primary winding 41 and with secondary windings 42, 43 and 44. The transformer 40 is a voltage regulating type of transformer and is provided with a primary 45 and a secondary 46. The primaries 41 and 45 are connected to conductors 47 and 48 which are adapted to be connected to a source of alternating voltage, not'shown.

The. secondary winding 42 of transformer 39 supplies operating voltage to the discharge devices 26 and 31,

the discharge device 26 being connected across the lower portion of the secondary winding and the discharge device 31 being connected across the upper'portion of the secondary winding.

The transformer secondary 43 provides "energizing voltage for the heaters of discharge devices 26 and 31 "13 and in conjunction with a rectifier 52 and the capacitor 53 this secondary winding providesbiasing volt .this time applied to the Geiger tube.

3 age to substantially bias the discharge device 13 to cut off.

The secondary winding 46 provides the high voltage utilized by the discharge devices 19 and 13 and the Geiger tube 10. This secondary winding is connected to a bridge rectifier 54 and the output of this rectifier charges 2. ca-

pacitor 55 to the polarity shown in Figure 1.

As above discussed, it is desirable to insure that operating voltage is not applied to the Geiger tube 10 until .the quenching circuit including discharge device 13 is operative to perform its quenching action. The present invention accomplishes this by providing an integrating meansoin the form of a capacitor 56 and a resistor 57. This series, connected resistor and capacitor integrating network is connected directly across the capacitor 55. Also, capacitor 56 is connected to the anode 14 and the cathode 16 of discharge device 13 and to the anode 11 and the cathode 12 of Geiger tube 10 to supply operating the cathodes of the various discharge devices are cool.

If operating voltage is now applied to the conductors 47 and48, the capacitors t), 51, 53 and 55 are charged substantially immediately to the polarities shown in Figure 1.

The various discharge devices are inoperative at this time since their cathodes are not as yet heated to an operating temperature. The Geiger tube is also inoperative. This Geiger tube is connected to the now charged capacitor 55 but due to the functioning of integrating network 5657, an operating voltage is not at The capacitor 56 does, however, begin to charge from the capacitor 55 and the bridge rectifier 54. This charg-' ing rateis controlled by the relative magnitudes of the capacitor 56 and the rmistor 57 and these components are chosen to bear a relationship to the heating time of the cathode 16 of discharge device 13 such that the voltage does not build up on capacitor 56 sufiiciently high to apply an operating voltage to Geiger tube 10 until the discharge device 13 is operative to perform its quenching function. This construction insures that the Geiger tube 10 will not go through a period of sustained discharge waiting for the quenching circuit, including the discharge device 13, to become operative. In this mannor, the improved control apparatus avoids the undesirable period of instability which may result due to a period of sustained discharge of Geiger tube 14 After a given time interval, the capacitor 56 becomes charged to substantially the same magnitude of voltage as present on capacitor 55 and likewise the discharge devices 13, 19, 26 and 31 are heated to operating temperature. At this time an operating voltage is applied both to the Geiger tube 10 and the discharge device 13.

'As above mentioned, discharge device 13 is a gas filled device and the integrating network 56-57 performs an additional function in preventing the application of the high operating voltage to the anode and cathode of this discharge device until the cathode is heated to an electronemissive temperature. This is particularly desirable in the'case of a gas filled device since there is a tendency for a gas filled device of this type to be damaged if high operating voltage is applied to the anode and cathode thereof while the cathode remains in a condition where it is not heated to an electron emissive temperature.

The apparatus of Figure 1 is now in a standby condition wherein the Geiger tube 10 is monitoring the area surrounding the tube for the presence of an ionizing condition, such as a fire. within the Geiger tubeionizes and a pulse of current {flow-siren; the anode to the cathode of the Geigertuhe.

If a fire does occur, the gas a and conductors 63, 64 and 65 and capacitor 66 to the lower plate of capacitor 56.

This current is a small magnitude current and very little charge is drained off capacitor 56 due to this current. However, this current flows through the high magnitude resistor 62 to develop a voltage which is applied to the control electrode 15 of discharge device 13. The polarity of this voltage is such that the upper terminal thereof is positive. This voltage opposes the biasing voltage developed on capacitor 53 and thereby renders discharge device 13 conductive.

The current flow circuit for discharge device 13 can be traced from the upper plate of capacitor 56 through "conductors 58, 59 and 67, discharge device 13, conductors 68, 63, 64 and 65, and capacitor 66 to the lower plate of capacitor 56. Discharge device 13 passes a high current and charges capacitor 66 such that its left hand plate is positive with respect to the right hand plate. The voltage present on capacitor 66 is added in opposition to the voltage on capacitors 56 and the algebraic sum of these two voltages becomes the operating voltage for both the Geiger tube 10 and discharge device 13. Because of the relative magnitudes of capacitors 56 and 66, capacitor 56 having a much larger capacitance value, thevoltage on capacitor 56 is not reduced appreciably and the voltage on capacitor 66 approaches that of capacitor 56. In fact, it is possible due to the inductance effects in the circuit including discharge device 13 to produce a flywheel eflect and to have capacitor 66 charge to a higher voltage than capacitor 56, thereby reversing the polarity of the'voltage on the discharge device 13 and the Geiger tube 10.

In this manner, the Geiger tube 10 and the discharge device 13 are both quenched. The Geiger tube 10, once it is quenched, .is insensitive to the presence of the fire and remains so until the charge on capacitor 66 leaks off to cause the voltage'on capacitor 56 to once again be effective to apply an operating voltage to the Geiger tube 10 and to the discharge device 13.

The charge on capacitor 66 leaks off through a circuit which can be traced from the left hand plate of this capacitor through the series connected resistors 69 and 70, connected in parallel with the series'connected resistors '71 and 72. The circuit is then completed through conductor 73, capacitor and conductors 74 and 75 to the right hand plate of capacitor 66. The rate at which this capacitor 66 may discharge is mainly determined by themagnitude of the resistors 69, 70, 71 and 72.

After a given time, the voltage or charge on capacitor 66 is dissipated through the above traced circuit and the voltage on capacitor 56 is again effective to apply an operating voltage to the Geiger tube 10 and to the discharge device 13. If a flame is still present in the vicinity .of the Geiger tube 10, the tube is again ionized and y the sequence of the events repeats itself, the Geiger tube '10 continuing to cycle or count at a rate determined by .thedischarge time of capacitor 66.

This counting develops a cyclic or periodic control voltage across resistors 70 and 72 as the charge on capacitor 66 is periodically dissipated through the above traced circuit. This voltage is of a polarity such that the upper terminal of both resistors 70 and 72 is positive .with'respect to the lower terminal. This voltage is applied to the control electrodes 21 and 22. of discharge device 19 to render the discharge device conductive. As

-more completely explained in the above mentioned coresistor 70, conductor 73, Capacitor 50, conductor 74, and

resistor 78 to the cathode 23 of discharge device 19. It. can be seen that in this circuit, the voltage developed across resistor 70 is in series opposition to the voltage .on capacitor 50. A further biasing circuit however exists from control electrode 22 through conductor 76. charged capacitor 51, conductor 75 and resistor 78 to cathode 23. The voltage developed across resistor 70 is effectively integrated and after a time period, the cutoff bias is removed from control electrode 22.

'Thecircuit including control electrode 21 can be traced from this electrode through conductor 79, resistor 72, conductor 73, capacitor 50, conductor 74, cathode resistor 78 to cathode 23 of this discharge device. The voltage developed across resistor72 is in series opposition to the voltage on capacitor 50 and the cutofi bias is removed from control electrode 21.

In the case of the inherent random background count of the Geiger tube, the voltage developed across the resistors 70 and 72 is applied directly to the control elec :trode 21 but is not applied to the control electrode 22 due to the fact that it requires a given number. of counts occurring at other than in infrequent rate'to charge capacitor 51 sufficiently to cause the cut off bias to be removed from capacitor 22. In this manner, the integration of the voltage applied to control electrode 22 with respect to the voltage applied .to control electrode 21 provides for discrimination against the background count of the Geiger tube Upon discharge device 19 being rendered conductive,

a voltage is developed across the load resistors in the anode circuit of this discharge device. The current conducting circuit of this discharge device can be traced from the upper plate of capacitor 55 through the conductors 80 and 81, resistor 82 connected in parallel with series connected resistors 83 and 84, discharge device 19, cathode resistor 78, and conductor 74 to a lower plate of capacitor 55. From this circuit it can be seen that a voltage is developed across resistor 83 such that the lowerterminal thereof is negative with respect to the .upper terminal. The lower terminal of resistor 83 is, connected by means of conductor 85 to the control electrode 30 of discharge device 26. The upper terminal of this resistor is connected by means of conductors 81, 80

and 86 to' the cathode 28 of this discharge device.

Normally, discharge device 26 is conductive. The

current flow circuit for this discharge device can be traced from the tap 87 provided on transformer secondary winding 42 through conductors 88 and 89, resistor 90,

conductor 91, discharge device 26 and conductors 92 and 9 3 to the lower terminal of the transformer secondary winding. The voltage developed across resistor 90 due to this above traced current flow is such as to bias discharge device 31 to cut off and thereby maintain relay 36 de-energized. However, upon the above mentioned negative voltage being applied to the control electrode 30 of dischargr device 26, due to the conduction of discharge device 1':

discharge device 26 is cut off orrendered non-conductive .and the voltage normally developed acrossresistor 90 no on this secondary winding. This current flow circuit 'energizes the winding 37 of relay 36 and causes switch '38 to closetothereby perform a control function which is indicative of the presence of flame at the Geiger tube Summarizingthis operation, in order for the relay 36 flto be energized, it is necessary that the Geiger tube 10 be subjected to a sustained counting rate rather than to infrequent background counts. This is necessitated by the integration of the control voltage applied to the control electrode 22 of discharge device 19. Furthermore, upon the initial application of voltage to the power line conductors 47 and 48, the integrating means including the capacitor 56 and the resistor 57 functions to prevent the application of operating voltage to the Geiger tube 10 or to the gas filled discharge device 13 until the cathode of this discharge device is heated to an operating temperature. The time delay or integration accomplished by the integrating means 5657 is related to the heat-up time of cathode 16 such that shortly after this cathode becomes heated to an electron emissive temperature, capacitor 56 becomes charged to a sufficiently high voltage to apply an operating voltage to the Geiger tube 10 and to the discharge device 13.

When the Geiger tube 10 is then subjected to an ionizing condition, the discharge device is rendered conductive to charge capacitor 66, and in fact it is possible that due to a fiy-wheel effect within the circuit including discharge device 13 capacitor 66 may be charged to 21 volt age of a higher magnitude than that present on, the capacitor 56. The algebraic sum of the voltages on capacitors 56 and 66 then becomes the operating voltage applied to the Geiger tube and to discharge device 13. This extinguishes or quenches the Geiger tube.

The capacitor 66 then discharges over a short period of time, this discharge rate determining the counting rate of the Geiger tube. The Geiger tube 10 is then again ionized and another count is experienced. The sustained counting of the Geiger tube 10 causes the discharge device 19' to become conductive. This in turn causes discharge device 26 to be cut off and this in-turn causes discharge device 31 to become conductive to energize relay 36.

Referring now to the modification of Figure 2, this modification differs from that of Figure 1, mainly in that a different type of integrating means is provided'to delay the application of operating voltage to the Geiger tube and the gas filled tube in the quenching circuit. In the apparatus of Figure 2, the integrating means includes a capacitor 135, a discharge device 94 and a resistor 134.

The Geigertube 10 of Figure 2 is identical to that of Figure 1 as is the gas filled discharge device 13 in the quenching circuit forthe Geiger tube. The output of discharge device 13 controls a further electronic stage including a discharge device 96 having an anode 97, control electrodes 98 and 99, cathode 100 and cathode heater 101. Discharge device 96 is connected in controlling relationship to a further discharge device 102 having an anode 103, a cathode 104, a cathode heater 105 and a control electrode 106. 1

Operating voltage is supplied by a transformer 107 having a primary winding 108 adapted'to be connected to a source of alternating voltage, not shown, by means of conductors 109 and110. Transformer 107 is provided with secondary windings 111, 112, 113 and 114. The transformer secondary winding 111 is provided with a tap and the upper portion of this winding is utilized in conjunction with a rectifier 115 and a capacitor 116 to provide operating voltage for the anode and cathode circuit of discharge device 102. The lower portion of this secondary winding is utilized in conjunction with rectifier 117 and capacitor 118 to provide a biasing voltage for discharge device 102.

The secondary winding 112 is connected to a bridge rectifier 119 which supplies a high magnitude D.C. voltage to capacitor 120, this voltage being of the polarity shown in Figure 2.

Transformer secondary winding 113 supplies operating voltage to the filaments of discharge devices 102 and 94 and also to the filament of discharge device 96. Furthermore, this secondary winding is utilized in conjunction with rectifier 121 and capacitor 122 to provide a source of direct current biasing voltage for the discharge device 96. This source of biasing voltage charges a capacitor 123 to the polarity shown in Figure 2. Capacitor 123 is connected to the control electrode 99 of discharge device operating voltage is applied to the power line conductors 109, and 110, thecapacitors 118, 120, 122, 123 and 125 are charged as shown in Figure 2. However, an operatmg voltage is notapplied to the Geiger tube 10 or the gas filled discharge device 13 due to the fact that capacitor-195 is not charged at this time. As above mentioned,

capacitor 195 in combination with the discharge device 94 and capacitor 135 functions asan integrating network.

Discharge device 94 is provided with an anode 126, a cathode 127, a control electrode 128, and a cathode heater 129. A given time period is required for the cathode 127 of this discharge device to be heated to an electron-emissive temperature. Upon this cathode being .so heated, discharge device 94 conducts through a circuit which can be traced from the upper terminal of capacitor 120 through conductors 130, 131 and 132, discharge device 94, conductor 133, resistor134, capacitor 135, and conductors 136, 137 and 138 to the lower plate of capacitor 120. .-From this. above traced circuit, it can be seen that as soon as current flows from the anodeto the cathode .of discharge device 94, this current develops a voltage across resistor 134 such as to bias dischargedevice 94toward cut off. This current flow also tends to charge capacitor .135. In this mannenthe resistance represented by the anode to cathode circuit of dischargedevice 94 remains very high and'the charging of capacitor 135 is considerably delayed. It will also be noted that the heatup time of cathode 127 also delays the charging of capacitor 195. a During this time delay period, capacitor 195 tends to charge through discharge device 94 through a circuit which can be traced from the upper terminal of capacitor 120 through conductors 130,- 131 and 132, discharge device 94, conductors 135 and 139, capacitor 195, conductor 140, series connected resistors 1 41 and 142 connected'in parallel with series connected resistors 143 and 144, and conductor 145 to the lower plate of capacitor 122. In this circuit it can be seen that the voltages present on capacitors 120 and 122 are in aiding relationship and tend to charge capacitor 195. However, due to the fact that discharge device 94 represents a very high impedancle1 at this time, the charging of capacitor 195 is very slig t.

After a suificienttimegperiod however, capacitor 135 charges to approximately the magnitude of voltage present on capacitor 120. The current flow through discharge device-94 and resistor 134, no longer biases discharge device toward cutoff .andtherefore discharge device 94 is rendered fullyconductive. Capacitor 195 may new charge through the abovetraced circuit including discharge device 94. The voltage on capacitor 195 then becomes of a sufiicient magnitude to' apply an operating voltage to the Geiger tube 10 and the discharge device 13.

The apparatus is now in a standby condition wherein the Geiger tube 10 is monitoring the space wherein the Geiger tube is positioned. If an ionizing condition occurs in this space, such .as-a fire, the Geiger tube 10 is ionized and the discharge device :13 is rendered conductive, much in the same manner as described in connection with Figure 1. The current conducting circuit for the Geiger tube 14} can be traced from the upper plate of capacitor 195 through conductor 139, resistor 146, conductor 147, Geiger tube 10, conductor 148, resistor 149, capacitor 125 and conductor 151) to the lower plate of capacitor 95. The current flowing in this circuit develops a voltage across resistor 149 which overcomes the bias voltage developed on capacitor 125 and causes discharge device 13 to becomeconductive. "Discharge device-13 as described.

conducts a high current compared to that passed by the Geiger tube and itscurrent flow circuit can be traced from theupper plate of capacitor 195 through conductor 1,39, resistor 146, conductor 1 51, discharge device 13 and conductors 152 and 150 to the lower plate of capacitor 95. f'lhis relatively high current in flowing through resistor 146 reduces the voltage applied to both the Geiger tube'lt and discharge device 13 so as to quench the Geiger tube 10." c

The conductionof discharge device 13 also reduces the charge or voltage on capacitor 195 and when Geiger tube 10 is quenched, the capacitor 195 recharges through a circuit which can be traced frorn the upper plate of capacitor 121) through conductors 130, 131 and132, discharge device 94, conductors 133 and 139, capacitor 195, conductor 140, series connected resistors 141 and 142 connected in parallel with series connected resistors 143 and 144, and conductor 145 to the lower plate of capacitor 1 2 2. It can be seen that the current flow in this circuit develops thevoltage across resistors 144 and 142 suchlthat the upper terminals of these resistors are positive with respect to the lower terminals. This applies a positive. voltage toboth of the 'control electrodes 98 and 5990f dischargeldevice 96. The voltage applied to the control electrode 9.8; is directly applied'thereto while the voltage applied to thecontrol electrode 99 is integrated,

The input circuit to control electrode 98 can be traced frorn'this electrode through conductor 160, resistor 142, conductor 145, capacitor 122, conductor 138 and resistor 161 tothe cathode of discharge device96. The circuit for control electrode 99 can be traced from this electrode ,tl rough conductor 1 62, resistor 144, conductor 145, ca-

pacitor 122, conductor138 an'd resistor 161 to the cathode of thisdischarge device. It can be seen that the voltage developed across resistors 142 and 144 due to the recharging current for capacitor 195 is of a polarity to oppose the voltage on capacitor 122, therebycausmg discharge device '96 to become conductive. With regard .to control electrode '99, however, a certain time period is necessary for capacitor 123 to discharge and this time delay provides for discrimination aganstthe background count of'the Geger tube 10, much as the capacitor 5 1 of the 'modification of Figure 1 performs this function.

This c'urren't' flow circuit for discharge device 96, once this device is' rendered conductive, can be traced from the upper plate ofcapacitor 120 through conductors 130 and 1-31, resistor 163, discharge device 96, resistor 161 and conductor 138 to the lower plate of capacitor 120. The currentfiowing in thiscircuit develops a voltage across resistor 163such that its upperterminal is positive Qwithiespezit'td the lower terminal. This positive voltage .is applied tofthe control electrode 106' through a further integrating network including resistor 164 and capacitor 165. The voltage'developed across capacitor 165 as the output voltage of discharge device 96 is integrated is of s'uch apolarity as to oppose the voltage present on capacitor 118, that is .the biasing potential applied to thecontrol electrode 106' This causes discharge device 102 to be rendered conductive and the winding of relay 124 is ener gized to close switch 167,

which is connected to a circuit to be controlled.

. From the above description it can be seen that the modification of Figure 2 provides a manner of controlling relay 124 in accordance with the condition to which the Geiger tube 10 is subjected. Furthermore, integrating means in the'form of the discharge device 94 and its associatedcircuitry' is provided to delay the application of operating voltage to the Geiger tube '10 of the gas v filledquenching tube 13 toprovide .for reliable operation of theGeiger tube 10, insuring that Geiger tube 10 may not go into a state ,ofsustained discharge while the cathode of the tube 13 isin a cold condition and the quench- -...ir su i pea s 19 as h t -es t Other modifications .of the present invention will be apparent to those skilled in the art and it is intended that the scope of the present invention be limited solely to r the scope of the appended claims.

I claim as my invention:

1. In combination; a non-selfquenching Geiger tube, a quenching circuit including a hot cathode discharge device, a source of voltage, circuit means connecting said Geiger tube to said quenching circuit in a manner to control said discharge device and to cause said Geiger tube to be quenched upon said Geiger tube experiencing an ionizing event, circuit means connecting the cathode of said discharge device to said source of voltage to cause heating thereof, and further circuit means including an integrating network connecting said Geiger tube to said source of voltage to thereby apply an operating voltage thereto, said integrating network having a time delay of suflicient length to delay the application of said operating voltage until the cathode of said discharge device has reached operating temperature, to thereby prevent a sustained discharge of said Geiger tube.

2. In combination; a non-selfquenching Geiger tube, a quenching circuit including a hot cathode electron discharge device, circuit means connecting the Geiger tube anode to the anode of said discharge device and the Geiger tube cathode to the control electrode of said discharge device, a source of voltage, circuit means directly connecting said source of voltage to the cathode of said discharge device to cause heating thereof to an operating temperature, integrating means, and circuit means connecting said Geiger tube anode to said source of voltage through said integrating means, said integrating means having a time delay of sufiicient lenth to delay the application of an operating voltage to said Geiger tube until said discharge device cathode is heated to said operating temperature and said quenching circuit is in a condition to quench said Geiger tube.

3. In combination; a non-selfquenching Geiger tube, a quenching circuit including a hot cathode electron discharge device whose cathode includes a heater and becomes electron emissive upon being heated to an operating temperature, means connecting said Geiger tube and said quenching circuit in controlling relation to each other such that ionization of said Geiger tube controls said discharge device to cause subsequent deionization of said Geiger tube, a source of A.C. voltage, rectifying means, means connecting said rectifying means to said source of A.C. voltage to provide a source of D.C. voltage, means connecting said cathode heater to said source of A.C. voltage to thereby heat said cathode to said operating temperature, integrating means, means connecting said integrating means to said source of D.C. voltage to integrate the output thereof, andmeans connecting the output of said integrating means to said Geiger tube, the time constant of said integrating means being sulficiently large to delay the application of an operating voltage to said Geiger tube until said discharge device cathode is heated to said operating temperature and said quenching circuit is in an operating condition.

4. Control apparatus comprising; a Geiger tube condition sensor having an anode and a cathode; an electron discharge device having an anode, a control electrode, a cathode of the type which becomes electron emissive upon being heated to an operating temperature, and an electn'cally energizable cathode heater; circuit means connecting the anode of said Geiger tube to the anode of a cathode and an electrically energizable cathode heater said discharge device, circuit means connecting the oathode of said Geiger tube to the control electrode of said discharge device; a source of A.C. voltage, rectifying means, circuit means connecting said rectifying means to said source of A.C. voltage to provide a source of D.C. voltage; integrating means in the form of a series connected capacitor and resistor connected to said source of D.C. voltage to integrate the output thereof, circuit means connecting the anode and cathode of said discharge device to said capacitor in such a manner that the voltage on said capacitor is the operating voltage of said discharge device and of said Geiger tube; further circuit means con necting said cathode heater to said source of A.C. voltage, said integrating means having an R.-C. time constant of sufficient magnitude to delay the application of an operating voltage to said discharge device and to said Geiger tube until said discharge device cathode is heated to said operating temperature, and control means controllde by said discharge device in accordance with the condition to which said Geiger tube is subjected.

5. Control apparatus as defined in claim 4, wherein said electron discharge device is a gas-filled electron discharge device.

6. Control apparatus comprising; a Geiger tube condition sensor having an anode and a cathode; a first electron discharge device having an anode, a control electrode,

arranged to heat said cathode to an electron emissive temperature; circuit means connecting the anode of said Geiger tube to the anode of said first discharge device and the cathode of said Geiger tube to the control electrode of said first discharge device, a source of operating voltage for said Geiger tube and said first discharge device; circuit means connecting said first discharge device cathode heater to said source of voltages; integrating means in the form of a second discharge device having its anode and cathode connected in series with a resistor and a capacitor to said source of voltage, with the control electrode of said second discharge device being connected to the junction of said resistor and said capacitor; circuit means connecting the anode of said first discharge device to the cathode of said second named discharge device and the cathode of said first discharge device to said source of voltage, said integrating means having a time delay of sufficient length to delay the application of an operating voltage to said first discharge device and to said Geiger tube until said first discharge device cathode is heated to said operating temperature, and control means controlled by said first discharge device in accordance to the condition of which said Geiger tube is subjected.

7. Control apparatus as defined in claim 6, wherein said first electron discharge device is a gas filled electron discharge device.

References Cited in the file of this patent UNITED STATES PATENTS 2,675,484 Hepp Apr. 13, 1954 2,695,364 Wolfe Nov. 23, 1954 2,721,276 Exner Oct. 18, 1955 2,783,388 Wintermute Feb. 26, 1957 I OTHER REFERENCES Electron and Nuclear Counters, by S. A. Korfi, copyright 1946 by D. Van Nostrand Co., pages 158 to 163 (printed January 1948). 

